- A micromechanical model for the growth of collagenous tissues under mechanics-mediated collagen deposition and degradation. [Journal Article]
- JMJ Mech Behav Biomed Mater 2019 Jun 07; 98:96-107
- In this study, we developed a micromechanical model for the growth and remodeling of a soft tissue based on the concurrent action of collagen deposition and degradation. We assumed in the model that …
In this study, we developed a micromechanical model for the growth and remodeling of a soft tissue based on the concurrent action of collagen deposition and degradation. We assumed in the model that collagen degradation causes a reduction in the fiber radius, while collagen deposition can increase both the radius and length of the collagen fibers growing under load. The latter arises from the assumption that collagen is deposited in an unstressed state, which increases the reference length of a fiber growing under mechanical load. The rate of collagen deposition and degradation can be stimulated and inhibited, respectively, by the fiber axial strain energy density. From these assumptions, we derived kinetic relationships for the fiber radial and axial growth stretch, and constitutive relations for the stress response and growth and remodeling of the tissues. We applied the model to study the growth of collagen fibers under a static and cyclic force. Cyclic force loading can drive the continual axial growth of collagen fiber, while the axial growth under a constant force eventually halts when an equilibrium state is reached. We then applied the model to investigate the development of stress and strain homeostasis of a spherical collagenous tissue membrane in response to a perturbation in the internal pressure. The model showed that an increase in the pressure produced growth in the tissue radius and thickness, such that the stress response was able to recover the equilibrium membrane stress before the pressure perturbation. Tissues composed of slender, or low-crimp collagen fibers also recovered the equilibrium mechanical stretch level before the perturbation. These results indicated that concurrent mechanics-stimulated collagen deposition and mechanics-inhibited degradation can produce stress homeostasis and for some fiber morphology strain homeostasis without prescribing a target stress or fiber strain.
- Evidence of mercury sequestration by carbon nanotubes and nanominerals present in agricultural soils from a coal fired power plant exhaust. [Journal Article]
- JHJ Hazard Mater 2019 Jun 06; 378:120747
- Mercury (Hg) in agricultural soils could have negative effects on the environment and the human health. The exposure to high level of Hg through different absorption pathways, such as ingestion and d…
Mercury (Hg) in agricultural soils could have negative effects on the environment and the human health. The exposure to high level of Hg through different absorption pathways, such as ingestion and diet through soil-plant system could permanently damage developing foetus of animals and humans. With the aim to assess the potential environmental and health risk and to study the behaviour and fate of Hg from agricultural soils to the environment, 47 soil samples were collected around a thermoelectric power plant in the Santa Catarina (Brazil). The Hg concentration measured by inductively coupled plasma mass spectrometry (ICP-MS) ranged from 0.16 to 0.56 mg kg-1. The distribution obtained by kriging interpolation allowed the identification of the main pollution sources. To see the morphology and composition of soil samples, field emission scanning electron microscopy (FE-SEM) and high resolution transmission electron microscopy (HR-TEM) were used combined with energy dispersive X-ray spectroscopy (EDS), showing that the carbon nanotubes and magnetite as nanomineral contributed to Hg retention. The mentioned molecular characterization, and the low Contamination Factors (CF) values obtained, suggested that there is low risk to the food security of the agro-ecosystems area near to the CFPP in the terms of Hg inputs and contamination.
- The tumor microenvironment is immuno-tolerogenic and a principal determinant of patient outcome in EBV positive Diffuse Large B Cell Lymphoma. [Journal Article]
- EJEur J Haematol 2019 Jun 18
- CONCLUSIONS: In EBV-pos DLBCL the TME is immuno-tolerogenic and may explain the poor outcomes seen in this subtype of DLBCL. This article is protected by copyright. All rights reserved.
- pH-Triggered Conformational Change of Antp-Based Drug Delivery Platform for Tumor Treatment with Combined Photothermal Therapy and Chemotherapy. [Journal Article]
- AHAdv Healthc Mater 2019 Jun 18; :e1900306
- Poor cellular uptake and low therapeutic efficacy of small-molecule antitumor drugs limit the application of drug delivery systems (DDSs) in cancer therapy. A conformational change of the Antp mimeti…
Poor cellular uptake and low therapeutic efficacy of small-molecule antitumor drugs limit the application of drug delivery systems (DDSs) in cancer therapy. A conformational change of the Antp mimetic peptide (AMP) in tumor microenvironments can greatly increase the cellular uptake as well as control drug release from a DDS. In this study, AMP-based nanoparticles (AMP-NPs) conjugated with tyroserleutide (YSL), an immunologically therapeutic tripeptide, are designed to encapsulate doxorubicin (Dox) and indocyanine green (ICG) to improve cellular uptake and cancer therapeutic efficacy by combining chemotherapy with photothermal therapy. In vitro studies verify that AMP-NPs can control the release of Dox and YSL at different pH values. Cell experiments show that AMP-NPs can promote the cellular uptake of Dox, and YSL can promote hepatocarcinoma cell (H22) apoptosis through downregulating Bcl-2 and cyclin D1 expression. In a mouse xenograft model using H22 cells, tumors are ablated when Dox- and ICG-loaded AMP-NPs are injected with the combination of hyperthermia effect induced by near-infrared (NIR) laser irradiation and chemotherapy from Dox and YSL. The pH-, photothermal-, and glutathione-responsive AMP-NPs with a conformational transition strategy can be utilized to synergistically enhance the cancer therapeutic efficacy with few side effects upon NIR laser irradiation.
- Methodology and application of Escherichia coli F4 and F18 encoding infection models in post-weaning pigs. [Review]
- JAJ Anim Sci Biotechnol 2019; 10:53
- The enterotoxigenic Escherichia coli (ETEC) expressing F4 and F18 fimbriae are the two main pathogens associated with post-weaning diarrhea (PWD) in piglets. The growing global concern regarding anti…
The enterotoxigenic Escherichia coli (ETEC) expressing F4 and F18 fimbriae are the two main pathogens associated with post-weaning diarrhea (PWD) in piglets. The growing global concern regarding antimicrobial resistance (AMR) has encouraged research into the development of nutritional and feeding strategies as well as vaccination protocols in order to counteract the PWD due to ETEC. A valid approach to researching effective strategies is to implement piglet in vivo challenge models with ETEC infection. Thus, the proper application and standardization of ETEC F4 and F18 challenge models represent an urgent priority. The current review provides an overview regarding the current piglet ETEC F4 and F18 challenge models; it highlights the key points for setting the challenge protocols and the most important indicators which should be included in research studies to verify the effectiveness of the ETEC challenge. Based on the current review, it is recommended that the setting of the model correctly assesses the choice and preconditioning of pigs, and the timing and dosage of the ETEC inoculation. Furthermore, the evaluation of the ETEC challenge response should include both clinical parameters (such as the occurrence of diarrhea, rectal temperature and bacterial fecal shedding) and biomarkers for the specific expression of ETEC F4/F18 (such as antibody production, specific F4/F18 immunoglobulins (Igs), ETEC F4/F18 fecal enumeration and analysis of the F4/F18 receptors expression in the intestinal brush borders). On the basis of the review, the piglets' response upon F4 or F18 inoculation differed in terms of the timing and intensity of the diarrhea development, on ETEC fecal shedding and in the piglets' immunological antibody response. This information was considered to be relevant to correctly define the experimental protocol, the data recording and the sample collections. Appropriate challenge settings and evaluation of the response parameters will allow future research studies to comply with the replacement, reduction and refinement (3R) approach, and to be able to evaluate the efficiency of a given feeding, nutritional or vaccination intervention in order to combat ETEC infection.
- Hepatitis C virus screening and treatment in Irish prisons from nurse managers' perspectives - a qualitative exploration. [Journal Article]
- BNBMC Nurs 2019; 18:23
- CONCLUSIONS: Prison nurses are uniquely placed to identify barriers and facilitators to HCV screening and treatment in prisoners and inform changes to health care practice and policy that will optimise the public health opportunity that incarceration provides.
- Abdominal aortic aneurysms that have ruptured or are at imminent risk of rupture. [Journal Article]
- RBRadiol Bras 2019 May-Jun; 52(3):182-186
- The rupture of an abdominal aortic aneurysm (AAA) is considered a high-risk surgical emergency, given the catastrophic consequences and high mortality rate. The objective of this pictorial essay is t…
The rupture of an abdominal aortic aneurysm (AAA) is considered a high-risk surgical emergency, given the catastrophic consequences and high mortality rate. The objective of this pictorial essay is to illustrate the radiological signs that indicate rupture or imminent rupture. To that end, we describe cases treated at our facility and present a brief review of the literature on the topic. The clinical diagnosis of imminent AAA rupture can be difficult, because patients are usually asymptomatic or have nonspecific pain complaints. In the subsequent follow-up, it is possible to identify radiological signs that indicate instability or rupture itself and thus change the prognosis. Computed tomography is the modality of choice for evaluating an AAA and abdominal pain in the emergency setting. It is therefore essential that the radiologist immediately identify the imaging findings that indicate AAA rupture or the imminent risk of such rupture.
- Current understanding of lymphatic vessels in the central nervous system. [Review]
- NRNeurosurg Rev 2019 Jun 18
- Lymphangiogenesis is associated with some pathological conditions such as inflammation, tissue repair, and tumor growth. Recently, a paradigm shift occurred following the discovery of meningeal lymph…
Lymphangiogenesis is associated with some pathological conditions such as inflammation, tissue repair, and tumor growth. Recently, a paradigm shift occurred following the discovery of meningeal lymphatic structures in the human central nervous system (CNS); these structures may be a key drainage route for cerebrospinal fluid (CSF) into the peripheral blood and may also contribute to inflammatory reaction and immune surveillance of the CNS. Lymphatic vessels located along the dural sinuses absorb CSF from the adjacent subarachnoid space and brain interstitial fluid via the glymphatic system, which is composed of aquaporin-4 water channels expressed on perivascular astrocytic end-feet membranes. Magnetic resonance imaging (MRI) clearly visualized these lymphatic vessels in the human dura mater. The conception of some neurological disorders, such as multiple sclerosis and Alzheimer's disease, has been changed by this paradigm shift. Meningeal lymphatic vessels could be a promising therapeutic target for the prevention of neurological disorders. However, the involvement of meningeal lymphatic vessels in the pathophysiology has not been fully elucidated and is the subject of future investigations. In this article, to understand the involvement of meningeal lymphatic vessels in neurological disorders, we review the differences between lymphangiogenesis in the CNS and in other tissues during both developmental and adulthood stages, and pathological conditions that may be associated with meningeal lymphatic vessels in the CNS.
- A map of the inorganic ternary metal nitrides. [Journal Article]
- NMNat Mater 2019 Jun 17
- Exploratory synthesis in new chemical spaces is the essence of solid-state chemistry. However, uncharted chemical spaces can be difficult to navigate, especially when materials synthesis is challengi…
Exploratory synthesis in new chemical spaces is the essence of solid-state chemistry. However, uncharted chemical spaces can be difficult to navigate, especially when materials synthesis is challenging. Nitrides represent one such space, where stringent synthesis constraints have limited the exploration of this important class of functional materials. Here, we employ a suite of computational materials discovery and informatics tools to construct a large stability map of the inorganic ternary metal nitrides. Our map clusters the ternary nitrides into chemical families with distinct stability and metastability, and highlights hundreds of promising new ternary nitride spaces for experimental investigation-from which we experimentally realized seven new Zn- and Mg-based ternary nitrides. By extracting the mixed metallicity, ionicity and covalency of solid-state bonding from the density functional theory (DFT)-computed electron density, we reveal the complex interplay between chemistry, composition and electronic structure in governing large-scale stability trends in ternary nitride materials.
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- Oxysulfide photocatalyst for visible-light-driven overall water splitting. [Journal Article]
- NMNat Mater 2019 Jun 17
- Oxysulfide semiconductors have narrow bandgaps suitable for water splitting under visible-light irradiation, because the electronegative sulfide ions negatively shift the valence band edges of the co…
Oxysulfide semiconductors have narrow bandgaps suitable for water splitting under visible-light irradiation, because the electronegative sulfide ions negatively shift the valence band edges of the corresponding oxides1,2. However, the instability of sulfide ions during the water oxidation is a critical obstacle to simultaneous evolution of hydrogen and oxygen3. Here, we demonstrate the activation and stabilization of Y2Ti2O5S2, with a bandgap of 1.9 eV, as a photocatalyst for overall water splitting. On loading of IrO2 and Rh/Cr2O3 as oxygen and hydrogen evolution co-catalysts, respectively, and fine-tuning of the reaction conditions, simultaneous production of stoichiometric amounts of hydrogen and oxygen was achieved on Y2Ti2O5S2 during a 20 h reaction. The discovery of the overall water splitting capabilities of Y2Ti2O5S2 extends the range of promising materials for solar hydrogen production.